In order to fixate a visual target or in scanning a field of interest, the eyes make one or more rapid eye movements, called saccades. Many of the neural populations that act together to produce these saccadic eye movements are located in restricted regions of the brainstem reticular formation. We propose to study these populations of premotor oculomotor neurons anatomically by proceeding in a stepwise manner, starting with the neurons in the motor nuclei that project into the extraocular muscles. In particular we will determine the populations of neurons that send axons into the motor nuclei, then study the anatomy of one group that produces a burst of spikes, called inhibitory burst neurons (IBNs), and a group of neurons that pause before a saccade, called omnipause neurons (OPNs). The IBNs drive motoneurons directly and OPNs appear to trigger the saccade. By using both anterograde and retrograde antomical tracers we will study the connections of these neuron populations. By this means, it will be possible to begin to demonstrate the pathways in the brain that are used to move the eyes saccadically. The inability to make rapid, accurate saccades results in numerous visual perceptual problems, especially if it occurs early in life, so an understanding of the processes controlling the genesis of will assist in understanding and perhaps correcting these types of visual problems. In addition, because onulomotor populations with differing influences on eye movements are distributed through a major portion of the brainstem, a knowledge of their location and role will be of clinical diagnostic importance. An examination of eye movements and their abnormalities will provide localizing signs for many neurological lesions.